Disk driving device and method for optical recording and reproducion with acceleration/deceleration of focusing means being based on a focus error signal level

Abstract

A disk driving device for use in recording and/or reproducing data on an optical recording medium having a plurality of recording layers. When a focus jump operation is executed between the recording layers, an actuator displaces an objective lens in response to a selectively generated acceleration or deceleration pulse and a focus error signal. Instability of the focus jump operation derived from noise superimposed on the focus error signal or from sensitivity variations in the actuator is eliminated.

What is claimed is: 
     
       1. Apparatus for driving a pickup for an optical recording medium having a plurality of recording layers, comprising: emitting means for emitting a light beam to impinge on said optical recording medium;   receiving means for receiving said light beam reflected from said optical recording medium;   focusing means having an adjustable focal point for focusing said light beam on a respective one of said plurality of recording layers;   driving means for accelerating or decelerating said focusing means in response to a focus jump command; and   control means for controlling acceleration or deceleration of said focusing means by said driving means during a predetermined period in which the focal point is displaced from one of said plurality of recording layers to another of said plurality of recording layers, said control means including focus error detector means for detecting a focus error signal level and being operable to selectively control said acceleration or deceleration based on the detected focus error signal level being within a reference range that is defined by a first predetermined threshold value and a second predetermined threshold value such that said acceleration is stopped when the detected focus error signal level is substantially equal to said first predetermined threshold value and said deceleration is started when the detected focus error signal level is substantially equal to said second predetermined threshold value.   
     
     
       2. The apparatus of claim 1, further comprising zero-crossing detector means for detecting when the level of the focus error signal is substantially zero; and wherein said control means is operable to halt the deceleration of said focusing means when said zero-crossing detector means detects the level of the focus error signal to be substantially zero. 
     
     
       3. The apparatus of claim 1, wherein said control means includes driving control means for decelerating said focusing means at a rate higher than an acceleration rate of said focusing means; and wherein said control means is operable to halt the deceleration of said focusing means when said focus error detector means detects that the level of the focus error signal is within said reference range. 
     
     
       4. The apparatus of claim 1, wherein said control means includes signal level detector means for detecting the signal level of said reflected light beam and reference value control means for modifying said reference range in accordance with said signal level of said reflected light beam. 
     
     
       5. The apparatus of claim 1, wherein said control means includes timer means for measuring a duration of deceleration of said focus means; and wherein said control means is operable to halt the deceleration of said focus means when the duration of said deceleration exceeds a predetermined period. 
     
     
       6. Apparatus for recording or reproducing data on an optical recording medium having a plurality of recording layers, comprising: emitting means for emitting a light beam to impinge on said optical recording medium;   receiving means for receiving said light beam reflected from said optical recording medium;   focusing means having an adjustable focal point for focusing said light beam on a respective one of said plurality of recording layers;   driving means for accelerating or decelerating said focusing means in response to a focus jump command;   control means for controlling acceleration or deceleration of said focusing means by said driving means during a predetermined period in which the focal point is displaced from one of said plurality of recording layers to another of said plurality of recording layers, said control means including focus error detector means for detecting a focus error signal level and being operable to selectively control said acceleration or deceleration based on the detected focus error signal level being within a reference range that is defined by a first predetermined threshold value and a second predetermined threshold value such that said acceleration is stopped when the detected focus error signal level is substantially equal to said first predetermined threshold value and said deceleration is started when the detected focus error signal level is substantially equal to said second predetermined threshold value; and   means for recording or reproducing data on said other of said plurality recording layers of said optical recording medium when the focal point is displaced to said other of said plurality of recording layers.   
     
     
       7. The apparatus of claim 6, further comprising zero-crossing detector means for detecting when the level of the focus error signal is substantially zero; and wherein said control means is operable to halt the deceleration of said focusing means when said zero-crossing detector means detects the level of the focus error signal to be substantially zero. 
     
     
       8. The apparatus of claim 6, wherein said control means includes driving control means for decelerating said focusing means at a rate higher than an acceleration rate of said focusing means; and wherein said control means is operable to halt the deceleration of said focusing means when said focus error detector means detects that the level of the focus error signal is within said reference range. 
     
     
       9. The apparatus of claim 6, wherein said control means includes signal level detector means for detecting the signal level of said reflected light beam and reference value control means for modifying said reference range in accordance with said signal level of said reflected light beam. 
     
     
       10. The apparatus of claim 6, wherein said control means includes timer means for measuring a duration of deceleration of said focus means; and wherein said control means is operable to halt the deceleration of said focus means when the duration of said deceleration exceeds a predetermined period. 
     
     
       11. A method for driving a pickup for an optical recording medium having a plurality of recording layers, comprising the steps of: focusing a light beam at a focal point on a respective one of said recording layers;   accelerating or decelerating an objective lens in response to a focus jump command, thereby displacing said focal point; and   controlling acceleration or deceleration of said objective lens during a predetermined period in which said focal point is displaced from one of said plurality of recording layers to another of said plurality of recording layers, said step of controlling including detecting a focus error signal level and selectively controlling said acceleration or deceleration based on the detected focus error signal level being within a reference range that is defined by a first predetermined threshold value and a second predetermined threshold value such that said acceleration is stopped when the detected focus error signal level is substantially equal to said first predetermined threshold value and said deceleration is started when the detected focus error signal level is substantially equal to said second predetermined threshold value.   
     
     
       12. The method of claim 11, further comprising the steps of detecting a focus error signal level; and displacing said objective lens at a constant speed during a period in which the focus error signal level is within a reference range. 
     
     
       13. The method of claim 12, further comprising the steps of detecting when the level of the focus error signal is substantially zero; and halting the deceleration of said objective lens when the level of the focus error signal is detected to be substantially zero. 
     
     
       14. The method of claim 12, further comprising the step of decelerating said objective lens at a rate higher than an acceleration rate of said objective lens; and halting the deceleration of said objective lens when the level of the focus error signal is detected within said reference range. 
     
     
       15. The method of claim 12, further comprising the steps of receiving the light beam reflected from the recording medium; detecting the level of said reflected light beam; and modifying the reference range in accordance with said level of said reflected light beam. 
     
     
       16. The method of claim 12, further comprising the steps of measuring a duration of the deceleration of said objective lens; and halting the deceleration when the duration of the deceleration exceeds a predetermined period. 
     
     
       17. A method for recording or reproducing on an optical recording medium having a plurality of recording layers, comprising the steps of: focusing a light beam at a focal point on a respective one of said recording layers;   accelerating or decelerating an objective lens in response to a focus jump command, thereby displacing said focal point;   controlling acceleration or deceleration of said objective lens during a predetermined period in which said focal point is displaced from one of said plurality of recording layers to another with said plurality of recording layers, said step of controlling including detecting a focus error signal level and selectively controlling said acceleration or deceleration based on the detected focus error signal level being within a reference range that is defined by a first predetermined threshold value and a second predetermined threshold value such that said acceleration is stopped when the detected focus error signal level is substantially equal to said first predetermined threshold value and said deceleration is started when the detected focus error signal level is substantially equal to said second predetermined threshold value; and   recording data on or reproducing data from said other of said plurality of recording layers of said optical recording medium when said focal point is detected within said proximity of said other of said plurality of recording layers.   
     
     
       18. The method of claim 17, further comprising the steps of detecting a focus error signal level; and displacing said objective lens at a constant speed during a period in which the focus error signal level is within a reference range. 
     
     
       19. The method of claim 18, further comprising the steps of detecting when the level of the focus-error signal is substantially zero; and halting the deceleration of said objective lens when the level of the focus error signal is detected to be substantially zero. 
     
     
       20. The method of claim 18, further comprising the step of decelerating said objective lens at a rate higher than an acceleration rate of said objective lens; and halting the deceleration of said objective lens when the level of the focus error signal is detected within said reference range. 
     
     
       21. The method of claim 18, further comprising the steps of receiving the light beam reflected from the recording medium; detecting the level of said reflected light beam; and modifying the reference range in accordance with said level of said reflected light beam. 
     
     
       22. The method of claim 18, further comprising the steps of measuring a duration of the deceleration of said objective lens; and halting the deceleration when the duration of the deceleration exceeds a predetermined period.